I'm putting together a simulation of the energy budget for a car driving the NEDC and FTP-75 emission drive cycles. I need to incorporate the effect of warmup enrichment for gasoline and diesel powertrains.

As a first approximation, I plan to simulate a simple heat capacity model of the engine thermal mass.

Can anyone help with data or references regarding how long (in seconds) a typical powertrain takes to warm up from cold to operating temperature on the two drive cycles?

Aside from the enormous scaling differences between the powertrain between a smart and a Ferrari that preclude "typical" from being of any use whatsoever ... diesels don't do warm-up enrichment. They'll use a little more after a cold start because of greater heat losses, more friction, glow plugs are often left on for a period of time after the engine starts which increases electrical demand, etc/gate valve., but by no means are they running "rich".

And, modern gasoline engines with good fuel injection also have minimum enrichment. It might be a smidge rich for the first couple of revolutions to make sure the engine starts, and it won't be able to run in closed-loop until the oxygen sensor starts giving a signal (and those are electrically heated and often very close to the engine, so this takes seconds nowadays), but given that the HC and CO emissions during cold start "count", they lean out ASAP after startup. Modern fuel injection minimizes (almost eliminates) "puddling" that necessitated enrichment in the old carbureted days. Modern fuel injection is capable of taking an extremely accurate "guess" at the required fuel volume even in the absence of the oxygen sensor signal. They'll use more fuel for the first little bit for all the same reasons that diesels do (above) with the exception of the glow-plug heating bit.

Most modern diesels don't have "glow plugs" anymore. And they typically adjust timing rather than fueling to make up for cold conditions, except for maybe a very transient early period. As stated above, most systems cannot afford to run an extensive cold cycle and still meet emissions, so they will try to line out to nominal conditions early.

Also, extreme cold conditions may not be emission controlled (less likely) or may have another emissions tier (more likely), so results may vary if the temperature is cold enough. What is cold enough depends on the regulations, engine size and application, and negotiations with EPA (or appropriate regulatory body), so there is no specific number to throw out there where you might see the change.

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